Process for the manufacture of unbleached paper, cardboard, and the like



Patented at. 3, 1931 UNITED STATES PATENT OFFICE PROCESS non THE MANUFACTURE or UNBLEAGHED PAPER, CARDBOARD, AND THE LIKE No Drawing. Application filed Kay 1, 1924, Serial No. 710,452, and in Germany May 25, 1928.

My invention relates. -to improvements in the manufacture of paper, cardboard and the like, and more particularly to a process for making paper, cardboard and similar pulp fabrics from dry grasses, reed-grasses, cereal-grasses and similar species of plants, and

of the incrustations, but also the largest porti on of the natural glutens or vegetableglues remain in the stuff together with the fibres and are not separated during the subsequent mechanical treatment in the presence of water, provided that vashing is not too severe during the mechanical process, or is omitted a ltogcther. The natural glutens or vegetable glues are therefore contained in the stuff in such quantities that it is not necessary to add further quantities of glue in order to obtain 0 a good paper. The part of the incrustatious which also remains inthe stuff, serves as till"- iug material.

- Instead of adding sizing and filling materials to the pulp, as in the ordinary process of as paper manufacture, my simplified process produces a pal or stuff, which is quite ready 1 or the manuihcture of unbleached paper, cardboard or the like without any addition of sizing or filling materials.

My improved process may be carried out in the following manner:

The dry raw material, for instance the straw of cereals. legumes, potatoes, grasses or'reeds is cut into a chatt'. The chaff, preferably after moistening, is introduced into a boiler and is steamed therein under pressure.

lhe pressure amounts to 5-6 atmospheres, and the steaming period lasts about 2 to 4 hours, according to the raw material employed. The thus steamed material is introduced into a rag-engine, an edge-mill or similar disintegrating or reducing apparatus, in which it is broken up into fibres in the presence of water up to the desired degree of fineness. During this treatment, the raw 1natc- 5 rial may also be washed. The pulp or stuff thus produced may directly be conveyed to the paper machine and be worked into unbleached paper, cardboard or the like.

In carrying out the above process the temperature and pressure as above indicated are adapted to the particular character of the raw material while the material is steamed as distinguished from being boiled or treated with hot water so as to retain the natural vegetable glues with the fibers, while most of the incrustations and cement substances are merely softened to a degree sufiicient to permit them to be broken up easily by subsequent mechanical treatment. I

The retention of the natural vegetable glues of the plants during the steaming operation results in these adhering to the fibers in the product resulting from the subsequent mechanical crushing with cold water in which the glues are not soluble.. As a result the final product contains so much glue that the pulp may be used to manufacture most solid papers and cardboards without any addition of glue whatefver, while the retention of the g incrustations results in the pulp containing a natural filler.

Hcretofore it has been proposed to remove the natural glues from wood, straw and the like by boiling or steaming and'to separat-g5 out or dissolve the incrustations by chemical treatment. My improved process is distin-' guished from these in that it sceksto retain the glue and the incrustations.

If the material is moistened or \i'ettcd prior to the steaming, thishas the advantage that the tendency of the material to spread is reduced to such an extent that the holding capacity of the steaming apparatus is considerably increased, and even doubled under certain circumstances. The wetting also leads to a uniformly good condition of the product of steaming. f

The pulp produced according to the improved process furthermore forms a suitable-(100.

half-stufi' .for the manufacture of bleached paper andcellulose. The product obtained by steaming and mechanical treatment is then subjected to a' further chemical decomposition. This decomposition may be eflected in the usual manner, for instance by boiling with caustic chemicals and subsequent bleaching with chloride of lime. For these purposes, my invention provides a process which may be carried out in uncivilized coun tries rich in plants of the described species by means of native labour, and which results in a half-stuff for the manufacture of bleached paper and cellulose. In order to obtain the half-stuff, the mechanical treatment is preferably carried only so far that the product consists of Well Washed raw fibres.

Preferably a sterilizing substance or agent may be added to the product,=in order to prevent rotting during the storage or the transort.

This half-stud can be pressed into bales,

.cakes or similar pieces (referred to as of my claims without departing from the spirit of my invention or sacrificing any of its advantages.

What I claim as my invention and desire to secure by Letters Patent is:

1. That process consisting in moistening a aveaoea integrated mass, and finally bleaching the decomposed mass.

In testimony whereof I have afixed my signature.

VALDEMAR WILLEMOES' DOBRY.

grass, steaming the moistened grass under pressure and preventing the escape of substantialy all of the constituents of said grass, and then mechanically disintegrating the mass.

2'. That process consisting in Wetting vegetable matter, steaming the Wet matter under pressure and preventmg the escape of substantially all of the constituents of said mat- I ter, and then disintegrating the mass.

. tially 3. That process consisting in moistening vegetable matter, steaming the moistened matter under pressure of approximately fivesix atmospheres, and preventing the escape of substantially all of the constituents of said matter, and then mechanically disintegrating the mass.

4. That process consisting in moistening a grass, steaming the moistened grass under pressure of approximately five-six atmospheres and preventing the escape of substanall of the constituents of said grass, disintegrating the mass, decomposing the dis- 

